IMPLANTES INTRAVERTEBRAIS EXPANSÍVEIS NAS FRATURAS VERTEBRAIS DORSOLOMBARES EM COMPRESSÃO

Moura, Diogo Filipe Lino; Gabriel, Josué Pereira

Diogo Filipe Lino Moura

Centro Hospitalar e Universitário de Coimbra, Orthopedics Department, Spine Unit, Coimbra, Portugal.

Universidade de Coimbra, Faculty of Medicine, Coimbra, Portugal.

Grant Medical Center, Spine Institute of Ohio, Columbus, OH, United States of America.

https://orcid.org/0000-0003-4037-2442

Josué Pereira Gabriel

Grant Medical Center, Spine Institute of Ohio, Columbus, OH, United States of America.

https://orcid.org/0000-0002-2129-1295

Correspondence: Diogo Filipe Lino Moura. Praceta Prof. Mota Pinto, Coimbra, Portugal, 3004561. dflcoluna@gmail.com

All authors declare no potential conflict of interest related to this article.

AUTHORS’ CONTRIBUTIONS:

Each author contributed individually and significantly to the development of this article. DFLM: intellectual concept of the article, literature review, data collection and analysis, writing of the article, final review of the article; JPG: intellectual concept of the article, literature review, data collection and analysis, writing of the article, final review of the article.

Figuras (3)
Tabelas (1)

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Figure 1
A: Indirect fracture reduction by distraction and lordosis maneuvers performed through instrumentation in the pedicles of adjacent vertebrae. Note the reduction of posterior wall retropulsion and restoration of anterior and posterior sagittal heights of the vertebral body. However, central flattening of the upper vertebral platform persists with no complete restoration of the middle sagittal height of the vertebral body (red arrowhead); B: Direct reduction of the fracture via expandable intravertebral implants. Note the elevation of the entire upper vertebral platform (arrowhead); C: Indirect reduction and direct reduction combined. Notice how direct reducion complements the indirect reduction manouvers, allowing the total anatomical restoration of the vertebral body, that is, the reduction of the cortical ring and also of the central portion of the vertebral platforms.

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Figure 2
Schematic representation of the objectives for each type of vertebral compression fracture, according to bone quality and the AOSpine classification, as well as the justification for choosing the expandable intravertebral implant to be applied and the need or not for pedicular instrumentation.

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Figure 3
Graphic algorithm of the surgical options for reducing and stabilizing each type of vertebral compression fracture according to the AOSpine classification. A1, A2, and A3 fractures according to AOSpine⁴⁴44. Vaccaro AR, Oner C, Kepler CK, Dvorak M, Schnake K, Bellabarba C, et al. AOSpine thoracolumbar spine injury classification system: fracture description, neurological status, and key modifiers. Spine (Phila Pa 1976). 2013;38(23):2028-37. - reduction and stabilization with SpineJack^® expandable intravertebral implants; A4 AOSpine fractures - initial reduction with maneuvers by pedicular instrumentation, additional reduction and replacement of the vertebral body with expansive intravertebral VBS^®-type implants filled with bone graft. Note the reduced central depression of the upper vertebral platform after expansion of intravertebral implants and its final filling with bone graft (final image in yellow/brown represents the bone graft inside the stents); Osteoporotic compression fractures - reduction and stabilization with expansive intravertebral VBS^®-type implants filled with bone cement. Note the reduced depressions of the upper and lower platforms after expansion of the implants. Final image in gray represents the cement inside the stents.

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Table 1
Features of the two main expandable intravertebral implants currently available. Indications of each implant according to the authors’ preference.42,43

Implant name	*VBS® (VertebralBodyStenting)*	SpineJack®
Illustration
Morphology	Cylindrical shape network (stent). Two implants by bipedicular access	Similar to a carjack with upper and lower lamellae. Two implants by bipedicular access
Material	Chromium-cobalt	Titanium
Expansion direction	Circumferential and centrifugal in the coronal plane (craniocaudal + lateral)	Bidirectional in craniocaudal or vertical direction
Expansion mechanism	Hydraulic, by a kyphoplasty ballon (pressure and volume controlled)	Mechanic
Expansion force	Maximum pressure of 30 Atm; Maximum expansion volumes: #Small stent = 4 ml; #Medium stent = 4.5 ml; #Large stent = 5 ml	Expansion force of 500 Newtons; Maximum expansion heights: #Small implant, 4.2 size = 12.5 mm; #Medium implant, 5.0 size = 17 mm; #Large implant, 5.8 size = 20 mm
Goal	Fracture reduction and space filling - Indicated for osteopenia, lithic injuries, and A4 burst traumatic fractures	Fracture reduction, preservation of non-fractured trabeculae - Indicated for A1, A2, and A3 fractures with healthy bones
Rationale	VBS® is a reduction and space-filling implant system since it can multidirectionally expand (vertically and laterally). It is indicated for reconstructing or replacing the vertebral body without waiting for vertebral fracture healing. Stents are implants that form two cavities, coated by a casing of impacted trabeculae, within the vertebral body by expanding and impacting surrounding bony trabeculae. These implants form cavities that, after being filled with cement or bone graft, replace much of the vertebral body, filling and stabilizing it. Moreover, they minimize cement extravasation by recreating the walls of the vertebral body via impaction of bony trabeculae containing the cement.	SpineJack® is a more powerful reduction implant and preserver of non-fractured native bone trabeculae, rather than a filler, as it has only vertical expansion and not lateral. In these cases, fracture reduction and healing is intended, rather than replacing the vertebral body. This implant only reduces and sustains the vertebral body since it shows neither cavitary shape nor lateral expansion. It is incapable of destroying intact lateral trabeculae and does not create significant empty space inside the vertebral body. Thus, it is useful when it is intended to reduce the fracture and obtain bone healing, preserving as much of healthy bone as possible. Therefore, we consider this implant not ideal for replacing the comminuted vertebral body, lytic or porotic, a vertebra that does not have content and needs intrasomatic filling in addition of fracture reduction.

[1] Correspondence: Diogo Filipe Lino Moura. Praceta Prof. Mota Pinto, Coimbra, Portugal, 3004561. dflcoluna@gmail.com

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IMPLANTES INTRAVERTEBRAIS EXPANSÍVEIS NAS FRATURAS VERTEBRAIS DORSOLOMBARES EM COMPRESSÃO

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